Class 11

Math

Algebra

Sequences and Series

Find $x$, if $2 ,x,2 1 $ are in G.P.

**Solution: **We know that the geometric mean between two numbers $a$ and $b$ is $GM=ab $.

Here, it is given that $GM=x$, $a=2 $ and $b=2 1 $, therefore,

$GM=ab ⇒x=2 ×2 1 ⇒x=1 ⇒x=1$

Hence, $x=1$